Companies that mail large numbers of paper items require high-speed paper-handling machines such as paper feeders that can handle thin sheets of paper as well as relatively thick paper such as paperboard, cardboard, and the like. It is sometimes advantageous to handle the paper while the paper is maintained in a flat configuration.
In a typical prior art feeder, paper is supported from below and conveyed through the feeder by a plurality of rotatably-mounted laterally-spaced apart transport belts. A rotatably-mounted fixed nip roller is positioned between the transport belts, also supporting the paper from below, and a single rotatably-mounted separator wheel is positioned above the paper in confronting registration with the fixed nip roller. The structure forms a hard nip point where each sheet of paper passes over the fixed nip roller and under the separator wheel. Such structure restricts the feeder to handling sheets having a common thickness and said structure cannot impart a wave-like or other shape to the paper.
However, sometimes it is advantageous to impart a wave-like configuration to the paper. This is commonly accomplished by positioning a first and second pair of transport belts beneath the sheets of paper on opposite sides of the fixed nip roller and by positioning first and second separator wheels above the sheets at locations that are staggered relative to the first and second pairs of transport belts, respectively. In this way, the separator wheels and transport belts are not in alignment with one another nor is a separator wheel in alignment with the fixed nip roller. Thus, no hard nip point is formed. The result is a wave-like shape for the paper where crest and troughs are formed by the absence of support. Specifically, a crest appears where a transport belt supports the paper from below but no separator wheel is positioned above said transport belt and a trough appears where a separator wheel engages the paper from above but no transport belt supports the paper from below.
A major drawback of the known feeders that impart a wave into the paper being handled is that they are restricted to paper having only a single thickness. A user must therefore purchase a first sheet feeder machine for forming thin sheets of paper into a wave and a second sheet feeder machine for forming thick sheets of paper into a wave.
It is known in the art to use staggered transport belts to create crests and troughs in a sheet of paper or other sheet material. The waves formed are intermittent, i.e., discontinuous, but the distinction between intermittent and continuous transport belts, rollers, and the like is well-known in this art. One example of such a prior art arrangement is depicted in U.S. Pat. No. 2,635,874 to La Bore. A machine that incorporates this known technology is also disclosed at www.straightshooterequip.com. That machine eliminates the nip roller and places a separator means above and between transport belts so that the paper is continuously deflected from the top by the separator means, thereby forming a trough, and continuously deflected from the bottom by the transport belts, thereby forming crests. This is a continuous version of the intermittent deflections produced by the known apparatus. The known machine mentioned above must be operating if the belt positions are to be adjusted.
What is needed, then, is a friction feeder apparatus that can handle and impart a wave structure into both thin sheets and thick sheets, and sheets having intermediate thicknesses.
There is also a need for such a machine that includes a nip roller that can be disposed in confronting relation to a separator wheel or disposed in downstream or upstream relation thereto.
A need exists as well for a machine that for safety purposes can be adjusted only while it is not operating.
However, in view of the prior art taken as a whole at the time the present invention was made, it was not obvious to those of ordinary skill how the identified needs could be fulfilled.